Doctors have come across some baffling day-to-day ailments, but few conditions are as strange as these 20 disorders, which range from biological to psychological to cultural in nature.

Foreign Accent SyndromeForeign accent syndrome (FAS) is a speech disorder that causes sudden changes in speech pattern, intonation and pronunciation so that the victim is perceived to speak with a “foreign” accent. FAS usually results from severe trauma to the brain, such as a stroke or head injury, and typically develops within one or two years of the injury. Of the 50 to 60 cases that have been verified since 1941, only a few FAS sufferers regained their normal speech pattern, although some experienced success through speech therapy.

Sexsomnia
Sexsomnia is a sleep disorder that, much like sleepwalking, compels the sufferer to engage in sexual activity while asleep. Identified in 2003, sexsomnia has since been cited to acquit defendants accused of sexual assault in British and Canadian criminal cases.

Exploding Head Syndrome
People with exploding head syndrome intermittently hear loud, explosion-like noises that seem to originate from within their own head. The “explosions” usually occur within an hour or two hours of the victim falling asleep. There’s no physical pain, but sufferers understandably experience fear and anxiety after such attacks. While it’s not clear what exactly causes the syndrome, it’s been linked to stress and fatigue and often vanishes without any treatment.

Fatal Familial Insomnia
Fatal familial insomnia (FFI) is a genetic sleep disorder that causes increasing sleeplessness, typically starting around the age of 50. The victim’s brain develops a plaque that inhibits the ability to sleep, and with less and less sleep, mental illness — including phobias, panic attacks, paranoia, dementia and hallucinations — set in. Within six months to three years after onset, the patient dies. There is no known cure.

Congenital Insensitivity to PainPeople with a congenital insensitivity to pain (CIPA) cannot feel physical pain, typically due to the mutation of a gene associated with the transmission of pain in the body. As such, they are more susceptible to death by trauma, since they might not be aware of the extent of damage done to their own bodies. There have been around 100 cases documented in the US.

Genital Retraction SyndromeGenital retraction syndrome (GRS) is a mental condition prevalent in specific cultures that causes sufferers to believe that their external genitals are shrinking or slowly disappearing into their bodies. The widespread belief of the occurrence in portions of Asia and Africa has led to so-called “penis panics,” episodes of mass hysteria in which thousands of cases, often tied to local beliefs in witchcraft, may be reported in a short period of time.

Werewolf Syndrome
Hypertrichosis, or werewolf syndrome, is a medical condition that causes the excessive growth of body hair — typically on the upper body, including the face.
There are only 50 or so documented cases, and sufferers generally acquire it through genetic inheritance. In 2008, scientists at Columbia University found that an injection of testosterone significantly helped in long-term hair loss in patients with hypertrichosis; the finding was hailed by many as a cure.

Pica
Pica is a compulsion to eat non-edible objects. Sufferers have been known to consume paper, dirt, paint, hair, glue, rocks, lint and laundry detergent. Related disorders include acuphagia (the eating of sharp objects) and hyalophagia (the eating of glass). There is no concrete cause, but pica is believed by many to result from a mineral deficiency, and as such, it’s found most frequently in pregnant women and children in lower-income areas.

Alice in Wonderland Syndrome
AIWS is a neurological condition that causes distorted visuals that make objects appear either much smaller (micropsia) or larger (macropsia) than they are. It’s a temporary condition that’s often associated with migraines, although it can also be caused by brain tumors and hallucinogenic drugs.

Capgras Delusion
The Capgras delusion is a mental condition in which the sufferer comes to believe that someone close to him — typically a spouse or family member — has been replaced by an identical imposter. The sufferer may continue to live peacefully (though distrustfully) with the “imposter,” or he may violently attack the loved one. Some people with Capgras delusion even second-guess their own reflections. The condition is typically caused by brain injury or mental illness like schizophrenia and dementia.

Alien Hand Syndrome
Also known as Dr. Strangelove syndrome and “anarchic hand,” AIS is a neurological disorder that makes the victim feel like he has lost control of one of his hands. In extreme cases, sufferers have been reported to engage in violent wrestling with their own hand, with the appendages even trying to strangle the patient while sleeping. Alien hand syndrome is caused by trauma to the brain — such as a stroke, aneurysm or head injury — and the symptoms can be treated, although the condition itself has no cure.

Stendhal Syndrome
Stendhal syndrome is the name given to a feeling of anxiety — dizziness, confusion, rapid heartbeat, even hallucinations and fainting — upon seeing beautiful works of art. The overwhelming sensation can come from the exceptional beauty of one particular piece of art or from the abundance of art in one location. The condition is most widely associated with the art of Florence, Italy, although it has been applied to similar reactions to overwhelming beauty of any type.

Walking Corpse Syndrome
Sufferers of walking corpse syndrome, also known as the Cotard delusion, believe that they are dead, decaying or have lost body parts or internal organs. In some cases, victims believe that they don’t even exist. Like the Capgras delusion, walking corpse syndrome is typically the result of brain damage or mental illness.

Jumping Frenchmen of Maine
Jumping Frenchmen of Maine is a form of the exaggerated startle reflex known as hyperexplexia, so named because it was first observed in French-Canadian lumberjacks in the Moosehead Lake region of Maine in 1878. Sufferers were reported to react abnormally to loud, sudden noises — screaming, flailing, muscle seizures and, most puzzlingly, obeying commands in a reflexive, involuntary manner. For instance, when instructed in a loud, authoritative voice to hit someone, they would do so without question. It’s believed to be a genetic condition caused by a blockage of an amino acid that calms the central nervous system.

Jerusalem Syndrome
Jerusalem syndrome is a form of religious mania resulting from, or leading to, a visit to the city of Jerusalem. Typically, a sufferer (of Christian or Jewish background) experiences a sudden religious fervor upon visiting the city, leading them to the belief that they are on a religiously significant mission and quite possibly that they are a specific biblical figure. People experiencing Jerusalem syndrome often end up dressing in a white robe and delivering a sermon at a religiously significant site in the city. Since 1980, there have been an average of close to 100 cases per year reported. It’s debatable whether or not sufferers had previous mental problems before visiting Jerusalem.

Spasmodic Dysphonia
Spasmodic dysphonia is a neurological disorder that causes involuntary movement of the larynx, causing muscle spasms that impair speech. Strangely, however, sufferers usually have no such hindrances when singing, whispering, laughing, speaking in a high pitch or even in rhymes. There is no known cure, although injections of Botox into the larynx have been shown to provide short-term relief.

Medical Students’ Syndrome
Medical students’ syndrome is a temporary, hypochondria-like mental condition that strikes medical students, causing them to believe that they are suffering from the diseases that they’re studying. By some reports, up to 80% of medical students experience it at some point as a result of studying such frightening diseases in such a highly suggestible environment.

Moebius Syndrome
Moebius syndrome is a neurological disorder that affects people from birth and is characterized by the inability of its sufferers to form facial expressions. People with Moebius syndrome are unable to move their facial muscles, meaning they can’t smile, frown, suck or even blink their eyes. They are also unable to move their eyes from side to side and have difficulty swallowing.

Fish Odor Syndrome
Fish odor syndrome, or trimethylaminuria, is a disorder that causes the sufferer’s breath, sweat and urine to give off a strong fishy smell (not that breath, sweat or urine otherwise have great odors). It’s caused by the inability of the body to break down a specific, fish-odored compound in foods. There is no cure, but sufferers can control the symptoms by avoiding certain foods and taking antibiotics.

Synesthesia
People with synesthesia (“synesthetes”) associate a stimulus with one of the five senses not typically related to it. For instance, they may describe a certain sound as having a color. There are several different types of synesthesia, mixing sight, sound, taste and other sensory elements, and by some estimates, as much as 5% of the population has some level of incidence. It’s a harmless condition and is often genetic, although some people have reported experiencing it as a result of a stroke or loss of sight or hearing. Perhaps because of its sensory nature, synesthesia is frequently reported amongst artists and musicians.